Internally Threaded Cap

ABSTRACT

A closure assembly for a tank includes a cap shell and a cylindrical insert connected by a lost motion connection defining a first stop and a second stop for relative axial movement. A dome extends inwardly from the cylindrical insert and includes an orifice defining a valve seat. A stem includes a mating edge for engaging the valve seat. The mating edge abuts the valve seat and displaces the dome axially to seal the orifice at the first stop, and is spaced from the valve seat to at the second stop. Opening the valve allows vapor to vent from the tank along a tortuous path defined through an aperture and between the cap shell and the cylindrical insert. The aperture is open or sealed with the valve depending on the relative position of the cap shell and cylindrical insert.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention relates to a closure assembly for a tank.

2. Description of the Prior Art

Certain tanks, such as fuel tanks, are selectively sealed and accessedthrough a closure assembly. In addition, known closure assembliesprovide a vent passage that selectively allows vapor to escape or enterthe tank.

SUMMARY OF THE INVENTION AND ADVANTAGES

The invention provides for a closure assembly including a cap shellhaving a top wall extending circumferentially about an axis to an outerperiphery. A cylindrical insert has a radial periphery facing the topwall of the cap shell and engages a fill neck of the tank. A dome issupported by the cylindrical insert and spaced axially from the radialperiphery. An orifice is formed on the dome and defines a valve seatextending circumferentially about the axis for fluid communication withthe tank. A stem has a mating edge and is spaced radially inward of theouter periphery and engages the valve seat with the mating edge to forma seal therebetween. The stem displaces the dome axially to form theseal.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present invention will be readily appreciated, as thesame becomes better understood by reference to the following detaileddescription when considered in connection with the accompanying drawingswherein:

FIG. 1 is a perspective exploded view of a closure assembly according toan exemplary embodiment of the invention;

FIG. 2 is a top view of the closure assembly of the exemplaryembodiment;

FIG. 3 is a front view of the closure assembly of the exemplaryembodiment;

FIG. 4 is a cross sectional view of the closure assembly taken alongline 4-4 of FIG. 2;

FIG. 5 is a cross sectional view of the closure assembly taken alongline 5-5 of FIG. 3;

FIG. 6 is a cross sectional view of a cap shell of the closure assemblytaken along a line similar to line 4-4 of FIG. 2;

FIG. 7 is a perspective view of a cylindrical insert of the closureassembly;

FIG. 8 is a cross sectional view of the cylindrical insert taken along aline similar to line 5-5 of FIG. 3; and

FIG. 9 is a cross sectional view of a tank detail of the closureassembly taken along a line similar to line 5-5 of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the Figures, wherein like numerals indicate correspondingparts throughout the several views, a closure assembly 20 for a tank isgenerally shown according to an exemplary embodiment in the explodedview of FIG. 1. A cap shell 22 is shown having a top wall extendingcircumferentially about an axis A to an outer periphery with a skirtdepending axially downwardly from the outer periphery of the top wall. Acylindrical insert 24 is shown with a radial periphery 26 extendingcircumferentially about the cylindrical insert 24 and facing the topwall of the cap shell 22 and a dome 28 supported by the cylindricalinsert 24 spaced axially from the radial periphery 26. Referring toFIGS. 4 and 5, the cap shell 22 is engaged with the cylindrical insert24 to define a tortuous path between the top wall of the cap shell 22and the radial periphery 26 of the cylindrical insert 24, and will bedescribed in more detail subsequently. The dome 28 has an orifice 30formed therein and defines a valve seat extending circumferentiallyabout the axis A for selective fluid communication with the tank. A stem32 with a mating edge 34 disposed at one end thereof is spaced radiallyinward of the outer periphery of the cap shell 22 and selectivelyengages the valve seat to form a seal.

A lost motion connection interconnects the cap shell 22 and thecylindrical insert 24, defining a first stop and a second stop. The lostmotion connection allows the cap shell 22 to move axially relative tothe cylindrical insert 24 between the first stop and the second stop.According to the exemplary embodiment, the lost motion connectionincludes a first cylindrical wall 36 depending axially downwardly fromthe top wall of the cap shell 22. Referring to FIG. 6, the firstcylindrical wall 36 is spaced radially inward of the skirt and radiallyoutward of the stem 32, and includes a male cap thread 38 having areverse thread pitch disposed thereabout. Referring to FIGS. 7 and 8,the lost motion connection further includes a female insert thread 40having a reverse thread pitch disposed about the cylindrical insert 24.Referring again to FIGS. 4 and 5, the female insert thread 40 engagesthe male cap thread 38 to axially move the cap shell 22 relative to thecylindrical insert 24 along the axis A between the first and secondstops in response to rotation of the cap shell 22. Alternatively thelost motion connection could comprise a tab and slot design (not shown)with slots that run circumferentially about the cylindrical insert 24 ina downwardly sloping fashion to achieve relative rotation and axialtranslation simultaneously, similar to that achieved by the male cap andfemale insert threads 38, 40. Another alternative could comprise slotsthan run axially along the length of the cylindrical insert 24, suchthat only axial translation is needed.

According to the exemplary embodiment, and referring again to FIG. 1,the lost motion connection also includes a pair of pins 42 that dependaxially downwardly from the top wall of the cap shell 22 and adjacentthe skirt. A guide track extends circumferentially about the cylindricalinsert 24 and receives the pins 42. The guide track is defined betweenthe radial periphery 26 of the cylindrical insert 24 and a radial shelf44 depending from the radial periphery 26. Referring to FIGS. 7 and 8,the radial shelf 44 also defines a notch 46 extending circumferentiallyabout the cylindrical insert 24 opposite, axially, of the guide track.The notch 46 receives a tank gasket 48, as shown in FIGS. 1 and 4, thatcontacts the cylindrical insert 24 and the tank and seals a spacetherebetween. Referring again to FIGS. 7 and 8, the lost motionconnection includes a pair of shoulders 50 that have a first side and asecond side. The shoulders 50 extend radially from the radial periphery26 of the cylindrical insert 24 and are spaced 180 degreescircumferentially from one another. The shoulders 50 engage each of thepins 42 against the first side to define the first stop and against thesecond side to define the second stop. A detent mechanism 52 is providedadjacent each of the shoulders 50 and extends radially into the guidetrack for maintaining the pins 42 against the shoulders 50 when the pins42 abut the second side. The lost motion mechanism therefore permits thecap shell 22 and the cylindrical insert 24 to rotate relative to oneanother between the first and second stops. Additionally, the cap shell22 rotates together with the cylindrical insert 24 in a cap insertiondirection when the pins 42 abut the first side of the shoulders 50, andthe cap shell 22 rotates together with the cylindrical insert 24 in acap removal direction when the pins 42 abut the second side of theshoulders 50.

The lost motion mechanism allows the stem 32 to displace the dome 28axially to form the seal when the cap shell 22 is moved to the firststop. According to the exemplary embodiment, this occurs when the pins42 abut the first side of the shoulders 50. The displacement is definedhere by a flexing, or deformation, of the dome 28 under pressure fromthe stem 32. The stem 32 is then spaced from the dome 28 when the capshell 22 is moved to the second stop, where the pins 42 abut the secondside of the shoulders 50.

Referring to FIGS. 4 and 5, the stem 32 of the exemplary embodimentdepends axially downwardly from the top wall. A distal edge of the stem32 defines the mating edge 34, and, as described earlier, the stem 32 isspaced radially inward of the first cylindrical wall 36 and defines anannular fluid chamber extending therebetween. In addition, the dome 28extends integrally and radially inwardly from the cylindrical insert 24.The stem 32 has a hollow center defining a second cylindrical wall. Acylindrical fluid chamber extends therein and is always in fluidcommunication with the tank, whether the pins 42 abut the first side orthe second side of the shoulders 50.

Referring to FIGS. 4 and 6, according to the exemplary embodiment, thefirst cylindrical wall 36 of the cap shell 22 includes an aperture 54between the top wall and the cylindrical insert 24. The aperture 54helps to define the tortuous path, which flows through the annular fluidchamber, through the aperture 54 and between the top wall of the capshell 22 and the radial periphery 26 of the cylindrical insert 24, andthen out to the environment. The aperture 54 is spaced from thecylindrical insert 24 to permit venting when the pins 42 abut the secondside of the shoulders 50, and the aperture 54 is covered by thecylindrical insert 24 to seal the tortuous path when the pins 42 abutthe first side of the shoulders 50. To assist the seal, an insert gasket56 is circumferentially aligned with the radial periphery 26 of thecylindrical insert 24 and is positioned intermediate the radialperiphery 26 and the top wall of the cap shell 22. The insert gasket 56contacts the cap shell 22 to seal the tortuous path when the pins 42abut the first side of the shoulders 50.

Additionally, the cylindrical insert 24 includes a male insert thread 58with a reverse thread pitch disposed thereabout for threadingly engaginga female neck thread 60 of the tank. Referring to FIGS. 1 and 9, a tankdetail 62 is shown having an annular flange 64 for engaging a tanksurface. This tank detail 62 may be separately manufactured from thetank body and then attached thereto during final assembly 20. If theparts are constructed of a suitable thermoplastic, they may be sonicwelded to complete the assembly 20. The tank detail 62 includes a fillneck 66 extending axially from the annular flange 64 and extends belowthe tank surface. The fill neck 66 includes the female neck thread 60threadingly engaging the male insert thread 58 of the cylindrical insert24. Finally, the fill neck 66 includes a neck flange 68 spaced axiallyfrom the annular flange 64 and spaced radially inwardly of the femaleneck thread 60. A neck gasket 70 is disposed radially on said neckflange 68 for contacting the bottom of the cylindrical insert 24.

The reverse thread pitch as described herein refers to a thread pitchhaving a flat or acute angle with respect to the thread to which itmates. This configuration helps to resist slippage resulting from axialforces generated by pressure within the tank. A conventional threadunder pressure could slip in a cap removal direction resulting inunwanted removal of the closure assembly 20 from the tank. The reversethread pitch may be alternatively referred to as a buttress thread.

According to the exemplary embodiment, the closure assembly 20 isoperated by rotating the cap shell 22 relative to the cap insert in acap insertion direction to press the stem 32 against the dome 28,engaging the valve seat with the mating edge 34, and displacing the dome28 axially by flexing it to create a seal for isolating the tank fromthe tortuous path. The assembly 20 can then be inserted onto the tankdetails 62 via the male insert threads 58 of the cylindrical insert 24engaging with the female neck threads 60 lining the fill neck 66. Inthis position, the tank is sealed from the environment and ready fortransportation. The reverse pitch, or buttress, threads 38, 40, 58, 60prevent pressure buildup from within the tank from inadvertently causingthe assembly 20 to rotate out in a cap removal direction. To open thevent, the cap shell 22 is then rotated in a cap removal direction andmoves relative to the cylindrical insert 24. This way, the distal edgeof the cylindrical insert 24 remains pressed against the neck gasket 70,but the stem 32 is axially spaced from the dome 28 to release the seal.Simultaneously, the aperture 54 of the first cylindrical wall 36 isspaced from the cylindrical insert 24. Vapor within the tank underpositive pressure can then escape the tank by flowing through theorifice 30 of the dome 28, through the annular fluid chamber, throughthe aperture 54 of the first cylindrical wall 36, and between the topwall of the cap shell 22 and the radial periphery 26 of the cylindricalinsert 24. This can be used, for example, with a fuel tank for a marineengine where venting is preferred during engine operation. The detentmechanism 52 also maintains the vent in the open position so thatvibrations from the engine do not cause the vent to inadvertently close.Finally, to remove completely the closure assembly 20, such as forrefueling in the provided example, the cap shell 22 and cylindricalinsert 24 can be rotated together by virtue of the pins 42 engaging thesecond side of the shoulders 50 until the entire assembly 20 isseparated from the tank.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings and may be practicedotherwise than as specifically described while within the scope of theappended claims.

1. A closure assembly for a tank comprising; a cap shell including a topwall extending circumferentially about an axis to an outer periphery, acylindrical insert having a radial periphery facing said top wall ofsaid cap shell for engaging a fill neck of the tank, a dome supported bysaid cylindrical insert spaced axially from said radial periphery, saiddome having an orifice formed therein and defining a valve seatextending circumferentially about said axis for fluid communication withthe tank, a stem having a mating edge and spaced radially inward of saidouter periphery for engaging said valve seat with said mating edge toform a seal therebetween, and said stem displacing said dome axially toform said seal.
 2. An assembly as set forth in claim 1 including a lostmotion connection between said cap shell and said cylindrical insertdefining a first stop and a second stop for moving said cap shellaxially relative to said cylindrical insert between said first stop andsaid second stop wherein said stem axially displaces said dome to formsaid seal when said cap shell is moved to said first stop and whereinsaid stem is spaced from said dome when said cap shell is moved to saidsecond stop.
 3. An assembly as set forth in claim 2 wherein said topwall of said cap shell and said radial periphery of said cylindricalinsert define a tortuous path therebetween when said cap shell is movedto said second stop and wherein said tortuous path is sealedtherebetween when said cap shell is moved to said first stop.
 4. Anassembly as set forth in claim 3 wherein said lost motion connectionincludes at least one pin depending from said cap shell and a guidetrack extending along said cylindrical insert for receiving said pin. 5.An assembly as set forth in claim 4 wherein said lost motion connectionincludes a detent mechanism for maintaining said cap shell against saidsecond stop to prevent inadvertent sealing of said valve seat.
 6. Anassembly as set forth in claim 5 wherein said lost motion connectionincludes a shoulder for maintaining engagement between said cap shelland said cylindrical insert to prevent separation.
 7. A closure assemblyfor a tank as set forth in claim 2 wherein said stem depends axiallydownwardly from said cap shell to a distal edge defining said matingedge.
 8. A closure assembly for a tank comprising; a cap shell includinga top wall extending circumferentially about an axis to an outerperiphery, a cylindrical insert having a radial periphery facing saidtop wall of said cap shell for engaging a fill neck of the tank, a domesupported by said cylindrical insert spaced axially from said radialperiphery, said dome having an orifice formed therein and defining avalve seat extending circumferentially about said axis for fluidcommunication, a stem having a mating edge and spaced radially inward ofsaid outer periphery for engaging said valve seat with said mating edgeto form a seal therebetween, a lost motion connection between said capshell and said cylindrical insert defining a first stop and a secondstop for moving said cap shell axially relative to said cylindricalinsert between said first stop and said second stop, said stemdisplacing said dome axially to form said seal and prevent fluidcommunication through said orifice when said cap shell is moved to saidfirst stop, and said stem spaced from said dome to allow fluidcommunication through said orifice when said cap shell is moved to saidsecond stop.
 9. An assembly as set forth in claim 8 wherein said lostmotion connection includes at least a pair of pins depending from saidtop wall of said cap shell and a guide track extending along saidcylindrical insert for receiving said pins.
 10. An assembly as set forthin claim 9 wherein said guide track extends circumferentially along saidcylindrical insert to allow relative rotation between said cap shell andsaid cylindrical insert when translating said cap shell between saidfirst and second stops.
 11. An assembly as set forth in claim 10 whereinsaid lost motion connection includes a first cylindrical wall dependingaxially downwardly from said top wall of said cap shell and spacedradially inwardly from said outer periphery and spaced radiallyoutwardly from said stem defining an annular fluid chamber extendingcylindrically therebetween and including a male cap thread disposedthereabout and wherein said cylindrical insert includes a female insertthread engaging said male cap thread for axially moving said cap shellrelative to said cylindrical insert along said axis in response torotation of said cap shell between said first and second stops.
 12. Anassembly as set forth in claim 11 wherein said stem depends axiallydownwardly from said top wall of said cap shell to a distal edgedefining said mating edge.
 13. An assembly as set forth in claim 12wherein said dome extends integrally and radially inwardly from saidcylindrical insert.
 14. An assembly as set forth in claim 12 whereinsaid stem includes a hollow center defining a second cylindrical walland a cylindrical fluid chamber in fluid communication with the tankwhen said cap shell is moved to both said first and second stops.
 15. Anassembly as set forth in claim 11 wherein said male cap thread and saidfemale insert thread each has a reverse thread pitch for resistingrotational slippage resulting from axial pressure.
 16. An assembly asset forth in claim 11 wherein said first cylindrical wall includes anaperture formed therein helping to define a tortuous path between saidcap shell and said radial periphery of said cylindrical insert.
 17. Anassembly as set forth in claim 16 wherein said aperture is covered bysaid cylindrical insert when said cap shell is moved to said first stopto seal said tortuous path and wherein said aperture is spaced axiallyfrom said cylindrical insert when said cap shell is moved to said secondstop to allow fluid communication across said tortuous path.
 18. Anassembly as set forth in claim 17 wherein said pins depend axiallydownwardly from said top wall and wherein said guide track includes aradial shelf depending from said radial periphery for axially engagingsaid pins.
 19. An assembly as set forth in claim 18 wherein said lostmotion connection includes a pair of shoulders each having a first sideand a second side and extending radially from said radial periphery ofsaid cylindrical insert and spaced circumferentially from one anotherfor engaging each of said pins on said first side when said cap shell ismoved to said first stop and for engaging each of said pins on saidsecond side when said cap shell is moved to said second stop.
 20. Anassembly as set forth in claim 19 wherein said lost motion connectingincludes a detent mechanism adjacent said second side of each of saidshoulders and extending radially into said radial shelf for maintainingsaid pins against said shoulders when said cap shell is moved to saidsecond stop.
 21. An assembly as set forth in claim 20 wherein saidmating edge of said stem abuts said valve seat when said pins abut saidfirst side of said shoulders and wherein said mating edge of said stemis spaced from said valve seat when said pins abut said second side ofsaid shoulders.
 22. A closure assembly for a tank comprising; a capshell including a top wall extending circumferentially about an axis toan outer periphery, said cap shell including a skirt depending axiallydownwardly from said outer periphery of said top wall, a cylindricalinsert having a radial periphery extending circumferentially about saidcylindrical insert and facing said top wall of said cap shell, said capshell engaged with said cylindrical insert to define a tortuous pathbetween said top wall of said cap shell and said radial periphery ofsaid cylindrical insert, a dome supported by said cylindrical insertspaced axially from said radial periphery, said dome having an orificeformed therein and defining a valve seat extending circumferentiallyabout said axis for fluid communication with the tank, a stem having amating edge disposed at one end thereof and spaced radially inward ofsaid outer periphery for selectively engaging said valve seat with saidmating edge to form a seal therebetween, a lost motion connectionbetween said cap shell and said cylindrical insert for defining a firststop and a second stop and for moving said cap shell axially relative tosaid cylindrical insert between said first stop and said second stop,said lost motion connection including a first cylindrical wall dependingaxially downwardly from said top wall of said cap shell and spacedradially inward of said skirt and including a male cap thread having areverse thread pitch disposed thereabout, said lost motion connectionincluding a female insert thread having a reverse thread pitch disposedabout said cylindrical insert and engaging said male cap thread of saidfirst cylindrical wall for axially moving said cap shell relative tosaid cylindrical insert along said axis between said first and secondstops in response to rotation of said cap shell, said lost motionconnection including a pair of pins depending axially downwardly fromsaid top wall of said cap shell adjacent said skirt and a guide trackextending circumferentially about said cylindrical insert for receivingsaid pins, said guide track including said radial periphery of saidcylindrical insert and a radial shelf depending from said radialperiphery for axially engaging said pins, said radial shelf of saidcylindrical insert defining a notch extending circumferentially aboutsaid cylindrical insert opposite of said guide track along said axis forreceiving a tank gasket to contact said cylindrical insert and the tankand to seal a space therebetween, said lost motion connection includinga pair of shoulders having a first side and a second side and extendingradially from said radial periphery of said cylindrical insert andspaced 180 degrees circumferentially from one another for abutting eachof said pins with said first side to define said first stop and forabutting each of said pins with said second side to define said secondstop, said lost motion connection including a detent mechanism adjacenteach of said shoulders and extending radially into said guide track formaintaining said pins against said shoulders when said pins abut saidsecond side, said cap shell and said cylindrical insert rotatingrelative to one another between said first and second stops and said capshell rotating together with said cylindrical insert in a cap insertiondirection when said pins abut said first side of said shoulders and saidcap shell rotating together with said cylindrical insert in a capremoval direction when said pins abut said second side of saidshoulders, said stem displacing said dome axially to form said seal whensaid pins abut said first side of said shoulders, said stem spaced fromsaid dome when said pins abut said second side of said shoulders, saidstem depending axially downwardly from said top wall to a distal edgedefining said mating edge and spaced radially inward of said firstcylindrical wall to define an annular fluid chamber extendingtherebetween, said stem having a hollow center defining a secondcylindrical wall extending axially therealong and a cylindrical fluidchamber extending therein in fluid communication with the tank when saidpins abut said first side and said second side of said shoulders, saiddome extending integrally and radially inwardly from said cylindricalinsert, said first cylindrical wall of said cap shell including anaperture between said top wall and said cylindrical insert helping todefine said tortuous path for venting said fluid chamber when said pinsabut said second side of said shoulders and said aperture covered bysaid cylindrical insert to seal said tortuous path when said pins abutsaid first side of said shoulders, an insert gasket circumferentiallyaligned with said radial periphery intermediate said radial peripheryand said top wall for contacting said cap shell to seal tortuous pathdefined when said pins abut said first side of said shoulders and forallowing fluid communication across said tortuous path when said pinsabut said second side of said shoulders, and said cylindrical insertincluding a male insert thread having a reverse thread pitch disposedthereabout for threadingly engaging a female neck thread of the tank.23. A closure assembly as set forth in claim 22 including; a tank detailhaving an annular flange for engaging a tank surface, said tank detailincluding a fill neck extending axially from said annular flange of saidtank detail for extending axially below the tank surface, said fill neckincluding said female neck thread threadingly engaging said male insertthread of said cylindrical insert, and said fill neck including a neckflange spaced axially from said annular flange and spaced radiallyinwardly of said female neck thread and a neck gasket disposed radiallythereon for contacting said bottom of said cylindrical insert.